The Siemens 3RT2015-2BB44-3MA0 is a SIRIUS power contactor in Size S00, meaning it's the compact frame for motor loads up to about 5.5 kW at 400 V AC-3. The 24 VDC coil pulls in reliably at 0.8 of rated voltage (19.2 V) and drops out cleanly; the spring-type terminals accept 0.5 to 4 mm² solid or stranded — no tool needed for the wire, just a screwdriver for the cage. It mounts via screw or snap-on onto 35 mm DIN rail per EN 60715, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward/backward, so panel layout constraints rarely block it.
The 24 VDC coil draws 6 A at rated value — that's the inrush to pull the armature in, not the hold current. Switching frequency tops out at 1 000 cycles/hour at AC-1 (resistive loads), drops to 750 at AC-3 (motor loads), and 250 at AC-4 (plugging/inching). For a conveyor start-stop cycle, 750 ops/hour is fine; for a rapid-reversing application, you'll hit the AC-4 ceiling.
Mechanical fit and environment
Dimensions: 45 mm wide, 70 mm high, 121 mm deep — the depth matters when the contactor sits behind a panel door with limited clearance. The spring-type terminals (solid or stranded 0.5 to 4 mm², or 2x 0.5 to 4 mm²) save wiring time compared to screw terminals, but verify the ferrule size if you're using stranded wire — the cage accepts ferruled ends fine.